The new head of the Pentagon's effort to combat the threat of roadside bombs says Iranian officials have apparently reduced their support for Iraqi Shiite Militias, cutting the supply of material for high-powered roadside bombs that can penetrate armored vehicles. Iraq's government spokesman says Iran has improved its attitude toward Iraq since a meeting between the two countries' leaders.

Lieutenant General Thomas Metz says the threat from what the military calls Explosively Formed Penetrators has fallen sharply in recent months. The high-powered bombs, usually placed by the sides of roads, propel molten copper at a passing vehicle, often with devastating effect. U.S. officials say the technology, materials and training needed to build the bombs comes from Iranian agents.

General Metz says the number of such bombs used or found in Iraq has fallen in recent months from as many as 80 per month to about 20. The general says the reduction appears to be the result of a decision by leaders of Iran's elite Quds Force, which the United States has accused of supplying the bombs.

Iraqi government spokesman Ali al-Dabbagh endorsed that view. Speaking at the Pentagon, he said Iran's attitude toward Iraq has improved, based partly on assurances provided by Iraqi Prime Minister Nouri al-Maliki to Iran's top leader Ayatollah Ali Khamenei.

"I think the personal relations formed between the prime minister and the supreme leader, with the commitment of the Supreme Leader of Iran that he is going to work not to allow [Iranian forces] to destabilize this [Iraqi] government, this also helped," said Ali al-Dabbagh. "The Iranians had noticed finally that the Americans, their presence in Iraq, is not going to be a threat for them."

The Iraqi spokesman says Iran understands the recent U.S.-Iraqi agreement to keep U.S. troops in Iraq for three more years will not threaten Iran's security.

The Pentagon statistics also indicate the overall number of roadside bombs in Iraq has also fallen sharply, from about 1,200 in April to 500 in October. But the statistics indicate that during the same period, the use of such bombs more than doubled in Afghanistan, with more than 250 per month since the spring.

The Iraqi official, Ali Al-Dabbagh, also said future U.S. and Iraqi governments might negotiate an extension of the U.S. troop presence beyond the end of 2011. He said it might be 10 years before Iraqi security forces can control the country without some foreign help with specialized capabilities, such as air support.

U.S. and Iraqi officials, and President-elect Barack Obama, have spoken about the need for some "residual" U.S. force in Iraq beyond 2011. Experts put the size of the force at perhaps 40,000, or 50,000 troops, about one third the size of the current force. Al-Dabbagh said as early as January, when the new agreement takes effect, he believes U.S. troops will begin doing less of the front-line fighting, leaving that more and more to Iraqi troops.

Ali al-Dabbagh also called for President-elect Barack Obama to begin a dialogue with Iranian leaders, as long as Iran agrees to respect international law and not interfere in the affairs of its neighbors. He said the United States should initiate a similar dialogue with Syria to further reduce tensions along Iraq's borders.